Transport Container

ABSTRACT

The present invention relates to a transport container for the acceptance of any desired articles or products comprising a plurality of wall elements surrounding a hollow space, wherein at least one of the wall elements has a wall sheet, wherein the wall sheet has an inwardly disposed layer and an outwardly disposed layer which are connected to one another by means of one or more walls spaced apart from one another and wherein the inwardly disposed and/or the outwardly disposed layer of the wall sheet is connected to a cover layer.

The present invention relates to a transport container for the acceptance of persons, any desired articles or products comprising a plurality of wall elements surrounding a hollow space.

Such transport containers can be used, for example, for freight transport on container ships, freight trains, etc. Transport containers usually have an inner container space which is surrounded by rectangular, large surface wall elements which form the side walls, the top and the base of the transport container. End walls are furthermore provided which have doors in one or both end walls.

The term “transport container” is understood as any desired space bounded by wall elements which is suitable for the transport of persons, freight and animals. In this respect, they can, for example, be ship transport containers, swap bodies for trucks or for transport by rail, structures for caravans, trailers, etc.

Such transport containers are available with and without heat insulation. In heat-insulated transport containers, the wall elements comprise a material of low thermal conductivity, e.g. a polyurethane foam, to achieve a high heat insulation.

Transport containers are subject to high loads in their use, e.g. on transport, on loading with cranes, forklift trucks, etc.; they are exposed to every weather and they must also withstand abuse. Two different design principles are to be distinguished with respect to the construction design of a transport container: support frame designs and self-supporting designs.

A support frame design comprises a load-bearing frame in accordance with FIG. 1 comprising corner posts 1, side members 2 and crossmembers 3. In such a design, the wall elements represent simple boundary elements and generally only make a small contribution to the structural strength and stiffness of the transport container. As can be seen from FIG. 1, the load-bearing frame comprises corner posts 1 and side members 2 and crossmembers 3 connecting the corner posts 1. The corner posts 1 and the members 2, 3 are e.g. steel sections or aluminum sections.

In contrast to this, with the self-supporting designs, the wall elements also, in addition to the frame, take up a substantial portion of the load acting on the transport container, which has the result that the frame can be made weaker and thus substantially lighter, for example by the use of thinner sections than in a support frame design.

The wall elements must have a high bending stiffness and bending strength. Wall elements with bending stiffness and bending strength are formed, for example, by a corrugated wall element such as is shown in FIG. 2. Such wall elements are used, for example, for transport containers without heat insulation.

A variant of a wall element which is used for transport containers with heat insulation and which results in high bending stiffness and bending strengths is the use of a light material, e.g. of a foam, in the interior of the wall element and of a relatively stiff and strong material as cover layers of the wall element. Such a structure with a light core and the two load-bearing cover layers is also called a sandwich design and is shown in FIG. 3. The cover layers are indicated by the reference numeral 4 and the wall core by the reference numeral 5. D indicates the total thickness of the sandwich wall element, dK the thickness of the wall core and dD the thickness of the cover layer.

The named support frame designs are widespread for transport containers both with and without heat insulation. A self-supporting lightweight construction design having a steel frame and sandwich wall elements made from a plywood core, that is of bonded wood, encapsulated by two fiberglass reinforced polyester resin cover layers is known, for example, from U.S. Pat. No. 3,561,633.

In the heat insulated transport containers having sandwich wall elements, a light, heat-insulating material, e.g. a polyurethane foam, is located in the wall core. The heat insulation of the wall element is substantially determined by the thickness and by the thermal conductivity of the heat-insulating material. A stiff and strong material is used for the cover layers covering the core at both sides, for example steel plate, aluminum plate or fiber-reinforced plastic. The stiffness and strength of the wall element is substantially determined by its total thickness and by the thickness, stiffness and strength of the two cover layers. In a known type of a heat-insulated ship container having sandwich wall elements, stainless steel plates of around 0.6 mm thickness are used for the side walls, for example, with a total wall thickness of around 65 mm. The weight of such a side wall amounts e.g. in a 20-foot container to around 225 kg with a foam in the core having a density of around 45 kg/m3.

A heat insulated wall element is furthermore known which manages without metallic components for the layers building the wall element. Such a wall element is known from U.S. Pat. No. 5,450,977. In the container known from this patent specification, the wall elements are bounded on each side by a layer comprising a non-metallic, relatively strong, light material having a relatively low thermal conductivity. A glass fiber/plastic composite is used, for example. The layers are connected to one another by C-shaped support channels which are preferably made of the same material. The C-shaped support channels as well as the named layers are first present as individual parts and are then connected to one another using RF welding technology on the manufacture of the container. The hollow spaces between the two layers and two respective adjacent C-shaped support channels are filled by a heat-insulating material.

In previously known wall elements in a sandwich design having metal cover layers and a foam located therebetween, one disadvantage is that these wall elements have a comparatively high weight. In the wall element known from U.S. Pat. No. 5,450,977, one disadvantage is that the outwardly disposed layer and the inwardly disposed layer are made from a heat-insulating material that moreover must have a high strength and stiffness and finally is exposed to weather influences or influences of container load so that high demands must be made on the outwardly disposed and inwardly disposed layers with respect to the material selection.

It is the object of the present invention to further develop a transport container of the initially named kind such that it is made comparatively lightweight with adequate strength and stiffness values and in which the aforesaid demands do not all have to be taken over by a layer of the wall element.

This object is solved by a transport container having the features of claim 1. Advantageous aspects of the invention form the subject of the dependent claims.

In accordance with the invention, at least one of the wall elements has a wall sheet, with the wall sheet having an inwardly disposed layer and an outwardly disposed layer which are connected to one another by means of one or more walls, with the inwardly disposed layer and/or the outwardly disposed layer of the wall sheet being connected to a separate cover layer. The cover layer is preferably the layer of the wall element forming the surface. An embodiment is equally covered by the invention in which further layers or coatings are arranged on the cover layer. Furthermore, the cover layer and the inwardly disposed and/or outwardly disposed layers of the wall sheet can be connected in a force-transmitting manner.

Accordingly, there are two layers, namely a layer belonging to the wall sheet and the cover layer, on the side or sides of the wall element on which the cover layer is located. The cover layer can, for example, be made of a stiff and strong material, whereas the layers of the wall sheet or the total wall sheet can be made, for example, from a lightweight material having a relatively low thermal conductivity. The demands to be made on the wall of a transport container can therefore be distributed arbitrarily onto the wall sheet, on the one hand, and onto the cover layer connected thereto, on the other hand. The cover layers can be directly connected to the layers of the wall sheet or can be separated therefrom by other layers disposed therebetween.

It is particularly advantageous if both the inwardly disposed layer and the outwardly disposed layer of the wall sheet are connected to a cover layer. In this manner, a sandwich wall element having a wall sheet core is formed, with the advantage also being obtained here that the demands on the properties of the wall element can be satisfied in a suitable manner by the wall sheet core, on the one hand, and by the cover layers, on the other hand. It is, for example, conceivable to make the wall sheets from a non-metallic, lightweight material having a relatively low thermal conductivity as a wall core and to use a stiff and strong material such as a steel plate, aluminum plate or a fiber-reinforced plastic, e.g. reinforced with fiberglass or carbon fibers, for the cover layers. This naturally also applies accordingly to the case that only one cover layer is provided.

A wall sheet is a sheet which is bounded by two layers which are connected to one another by one wall, or preferably more walls, with the walls preferably being made throughgoing.

All the wall elements of the transport container, that is, the two side walls, the top, the base and the two end walls, preferably have the design in accordance with the invention.

The cover layer or layers can be a non-metallic or metallic material, preferably of high stiffness and strength.

The walls of the wall sheet can have a length which corresponds to that of the wall element. The cover layers can, however, also project beyond the wall sheet, i.e. the wall sheet and thus also the walls can be shorter than the wall element. Provision can be made that the wall element has a shorter side and a longer side, with the walls of the wall sheet preferably extending parallel to the shorter side. Provision can generally also be made that the walls extend parallel to the longer side of the wall element. Provision can generally also be provided that the sides of the wall element have an identical length.

It is particularly advantageous if the wall sheet is made of a non-metallic material. The wall sheet can be made, for example, of a plastic, in particular from a thermoplastic or a thermosetting plastic which can be processed thermoplastically or from a thermosetting plastic. The selection of a suitable thermoplastic or of a thermosetting plastic which can be processed thermoplastically or of a thermosetting plastic is arbitrary. The wall sheet can be produced particularly advantageously when it is a case of a thermoplastic; for example a polypropylene, a polyamide, a styrol copolymer, a polyester such as polyethylene terephthalate or multicomponent polymer blend having one of the aforesaid polymers as one of the blend components can be considered. Other plastics such as biopolymers can also be used. It is in this respect preferably a light material having a relatively low thermal conductivity. In contrast to the initially named U.S. Pat. No. 5,450,977, the wall sheets do not necessarily have to comprise a strong and stiff material as there the cover layers and the C-shaped support channels. They can rather comprise a lightweight, preferably non-metallic, material which has a low thermal conductivity and thus takes over the substantial part of the heat insulation.

Fillers can be added to the plastic of the wall sheet to increase the shape resistance, to reduce the thermal conductivity of the plastic walls and/or to reduce the material price by a filler which is more cost-effective compared with the plastic. Wood flour, cellulose fibers, glass fibers, carbon fibers, microporous or nanoporous glass powder and other materials can be used as fillers, for example. If fillers are used, the filler material should have a density which is as low as possible, preferably less than 3000 kg/m3, even more preferably less than 2000 kg/m3, to keep the weight of the wall sheet as low as possible.

In a further embodiment of the present invention, provision is made that the wall or walls as well as the layers of the wall sheet are manufactured in one production step and are made in one piece. The wall or walls as well as the layers of the wall sheet are preferably manufactured continuously by means of extrusion. It is, for example, conceivable that the wall sheets are manufactured by means of profile extrusion, a customary processing method of plastic processing, in a width possible using this process (common extrusion widths are within the range up to 1 m; but wall sheets with a width of up to 3 m are also extruded), with them being able to be manufactured cost-effectively from one and the same material in a continuous processing process in a throughgoing process step. The walls can, however, also comprise a different plastic than the inwardly disposed layer and/or outwardly disposed layer, e.g. by the use of a so-called coextrusion. A subsequent connection of the walls by both layers is omitted with such an embodiment of the invention since it takes place in the coextrusion tool in which the melt flows of the coex materials flow together. To keep the heat flow in the wall sheet and thus the heat transfer through the walls as low as possible, it is generally advantageous to make the walls as narrow as possible and the spacings as large as possible under mechanical aspects of the total design.

Provision can be made that a plurality of walls are arranged and that the hollow spaces located between the walls are filled with a heat-insulating material. The heat-insulating material can be introduced efficiently into the hollow spaces either subsequently, e.g. a 2K polyurethane foam or foamed particle foam spheres of expanded polystyrene (EPS) or expanded polypropylene (EPP), or as a foam simultaneously in the process step of the wall sheet extrusion as an extrusion foam by means of so-called coextrusion, e.g. a polypropylene foam or a polystyrene foam. It is naturally equally conceivable that the hollows spaces are not filled.

In a further advantageous embodiment of the present invention, a plurality of walls are provided, with there being a vacuum in the hollow spaces between the walls or with prefabricated evacuated vacuum panels being introduced into the hollow spaces. A very good heat insulation is thereby achieved which exceeds the heat insulation of foam core sandwich plates of the same thickness by a multiple. Provision can generally be made that all the hollow spaces between the walls or only a part of the hollow spaces are evacuated or are provided with prefabricated evacuated vacuum panels.

The evacuated hollow spaces are naturally sealed in a suitable manner against air inflow. In the case of the introduction of prefabricated commercially available vacuum panels, the sealing of the hollow spaces against air inflow is not necessary since the vacuum panels are already vacuum-tight per se.

In the event that the vacuum cannot be held, for example due to damage or to a defective seal, provision can be made that filler bodies, for example polystyrene balls, are received in the evacuated regions. It can hereby be prevented that the air then located in the hollow spaces circulates, which would have the consequence of a further reduction in the heat insulation. There are no restrictions at all with respect to the type, size or arrangement of the filling bodies.

Provision is made in a further embodiment of the present invention that the inwardly disposed layer and/or the outwardly disposed layer of the wall sheet is/are adhesively bonded to the cover layer. The selection of the adhesive is dependent on the combination of materials of which the inner layer and the outer layer belonging to the wall sheet are made. If the wall sheet, and thus inner layer belonging to the wall sheet, is made e.g. of polypropylene filled with wood flour and if the cover layer is made, for example, of aluminum sheet, a 2K polyurethane adhesive can e.g. e used.

The cover layer and the wall sheet can also be connected to one another by any desired other techniques. It is also conceivable that the cover layer and the wall sheet are manufactured in one production step, for example by coextrusion, or are connected to one another during the extrusion process in the tool or in the calibration, where at least the surface of the wall sheet is still molten and adheres in this manner to the cover layer.

Provision is made in a further advantageous embodiment of the present invention that the wall elements comprise individual segments of wall sheet elements, preferably wall sheet strips, which are connected to one another. The inwardly disposed layer and/or the outwardly disposed layer of the individual wall sheet elements can be provided with a cover layer. In a preferred embodiment of the present invention, provision is made in this respect that the wall sheet elements or wall sheet strips are releasably connected to one another. Such a design not only facilitates the manufacture of the wall sheets, but also makes it possible that, in the event of damage, not the total wall sheet has to be replaced, but rather only the affected wall sheet strip. This procedure makes the repair of the transport container in accordance with the invention less expensive and simpler.

An example for such a releasable connection of the wall sheet elements or wall sheet strips is the tongue and groove system with a tongue which is provided in a marginal region of a wall sheet strip and which engages into a groove in the marginal region of the adjacent wall sheet strip.

It is generally equally conceivable to make the connection of the individual wall sheet elements or wall sheet strips by an unreleasable technique, for example by adhesive bonding or welding. In this respect, the connection of the individual wall sheet elements to the total wall element can e.g. take place in that only the cover layers are connected to one another. Any hollow spaces which are present between the wall sheet cores of adjacent wall sheet wall elements can in this respect be filled subsequently e.g. with a foam, e.g. a 2K PUR foam.

Provision is made in a further embodiment of the invention that the transport container has a self-supporting design.

The transport container can naturally also have a support frame design such as most of the ship containers currently in use. In this case, instead of the side wall sandwich elements, base sandwich elements, top sandwich elements and end wall sandwich elements with a foam core corresponding to the prior art, at least one of these elements can be used against the wall sheet sandwich elements described in the invention having a wall sheet in the interior and cover layers located thereon. If e.g. wall sheet wall elements with metallic cover layers are used, the metallic cover layers can be welded in a force-transmitting manner along their outer contours e.g. to the members of the support frame design or to the metallic cover layers of adjacent wall elements.

The wall elements in accordance with the invention are heavy duty, in particular have bending stiffness and bending strength, with a low weight. The exact dimensions of the wall elements with wall sheet, such as the total thickness, the thickness of the outer layer, the thickness of the inner layer, the wall thickness, the number of walls or the angle between the walls and the two layers can be set within a wide spectrum depending on the demand.

Further details and advantages of the present invention will be explained in more detail with reference to an embodiment shown in the drawing. There are shown:

FIGS. 1 to 3: different views of transport containers and wall elements in accordance with the prior art;

FIGS. 4 a, b: a perspective sectional view of a wall element in accordance with the invention (FIG. 4 a) and a schematic view of obliquely arranged walls (FIG. 4 b);

FIG. 5: a schematic perspective view of the transport container with a self-supporting design; and

FIG. 6: a sectional representation of a corner region of the transport container with angled sections connecting the wall elements.

FIG. 4 a shows a sectional representation of an embodiment of the wall element 10 in accordance with the invention with a wall sheet core 20. The wall sheet core 20 has an inwardly disposed layer 22 and an outwardly deposed layer 24. These layers 22, 24 are connected to one another by means of a plurality of throughgoing walls 26. Hollow spaces 27 are located between the walls 26. The wall thickness is marked by dS in FIG. 4 a; the wall spacing by the reference symbol b. The reference symbol dDI denotes the thickness of the inwardly disposed layer 22. The outwardly disposed layer 24 of the wall sheet 24 has a corresponding thickness. The wall sheet 20 is made in one piece and was manufactured from one and the same material in a continuous processing process. It comprises a thermoplastic.

The thickness of the wall sheet 20 is denoted in FIG. 4 a by the reference symbol DS and the total wall thickness of the wall element 10 is denoted by D.

The wall sheet 20 is adhesively bonded to cover layers 30 at its inner side and outer side. Said cover layers comprise a non-metallic or metallic material such as aluminum, steel or fiber-reinforced plastic. The cover layers 30 each have an identical thickness dDA. FIG. 4 b shows a wall sheet 20 with obliquely extending walls 26.

FIG. 5 shows a perspective schematic representation of a transport container in accordance with the invention in a self-supporting design. A frame 40 is provided in both end regions of the transport container which has no side members. The frame 40 comprises, for example, steel, aluminum or fiber/plastic composite sections. The side elements, the cover and the base form the envelope 50 and comprise sandwich wall elements 10 having a wall sheet core in accordance with the present invention. Provision can alternatively be made that the wall elements have a wall sheet having only one cover layer. As results from FIG. 6, the wall elements 10 adjacent to one another and forming the envelope 50 are connected at their inner and outer sides to angled metallic or non-metallic sections 60.

An example for a technical embodiment will be set forth in the following:

Wall Sheets:

Wall thickness 0.5-5 mm; thickness of the wall sheet 10 to 150 mm; walls arranged perpendicular to bands or at an angle up to 45° (lattice); wall spacing between 0.1 fold and tenfold the thickness of the wall sheet.

Foam:

Attached into the hollow chambers of the wall sheets either by means of coextrusion in a step in the profile extrusion or subsequently.

Cover Layers:

Steel 0.1-1.0 mm; aluminum 0.3-1.8 mm; fiber-reinforced plastic 0.1-2 mm.

Design:

Self-supporting design with a frame without side members in accordance with FIG. 5, e.g. made of steel/aluminum or fiber plastic composite sections and an envelope comprising sandwich wall elements having a wall sheet core, with the wall elements being connected inwardly and outwardly at the edges to rectangular metallic or non-metallic angled sections (FIG. 6). Support frame design with end frame and side members, e.g. made of steel/aluminum or fiber plastic composite sections and an envelope comprising sandwich wall elements having a wall sheet core.

In an embodiment in accordance with FIG. 4 a, the wall thickness dS and the thickness dDI of the inwardly deposed layer 22 and of the outwardly disposed layer 24 can amount to 1.5 mm. The total thickness D of the wall element amounts to 65 mm. The walls 26 stand perpendicular on the inwardly disposed layer 22 and on the outwardly disposed layer 24. The wall spacing b amounts to 65 mm. A stainless steel plate having a thickness of 0.3 mm is provided at both sides as cover layers 30. The hollow spaces located between the walls are foam-filled with a polyurethane foam of 30 kg/m3.

For such a wall element, a weight of around 140 kg results for such a side wall of a 20-foot container. In comparison with the side wall already described on the basis of a sandwich wall element having a thickness of 65 mm, a foam core and a 0.6 mm stainless steel plate, the sandwich wall element having a wall sheet core has fivefold the bending stiffness with a weight advantage at around 85 kg, with around the same heat insulation. If prefabricated vacuum panels are inserted into the hollow chambers of the wall sheets, an around 30% better heat insulation results with around the same weight. 

1. A transport container accepting persons, any desired articles or products, comprising: a plurality of wall elements surrounding a hollow space, wherein at least one of the wall elements has a wall sheet, wherein the wall sheet has an inwardly disposed layer and an outwardly disposed layer which are connected to one another by one or more walls spaced apart from one another, and wherein the inwardly disposed and/or the outwardly disposed layer of the wall sheet is connected to a cover layer.
 2. The transport container in accordance with claim 1, wherein both the inwardly disposed layer and the outwardly disposed layer of the wall sheet are connected to the cover layer.
 3. The transport container in accordance with claim 2, wherein in that the cover layer and the inwardly disposed layer and/or outwardly disposed layer of the wall sheet are of equal area and lie flush on one another.
 4. The transport container in accordance with claim 2, wherein the cover layer is larger in area than the inwardly disposed layer and/or outwardly disposed layer of the wall sheet and projects partially or wholly beyond it.
 5. The transport container in accordance with claim 2, wherein if the wall element has a shorter side and a longer side, and wherein the walls of the wall sheet extend parallel to the shorter side and/or to the longer side.
 6. The transport container in accordance with claim 1, wherein the wall sheet comprises a non-metallic material.
 7. The transport container in accordance with claim 6, wherein the wall sheet comprises a plastic, a thermoplastic or a thermosetting plastic which can be thermoplastically processed or a thermosetting plastic.
 8. The transport container in accordance with claim 7, wherein the plastic is a polypropylene, a polyamide, a styrol copolymer, a polyester or a biotechnologically manufactured polymer or a multicomponent polymer blend having one of the aforesaid polymers as one of the blend components.
 9. The transport container in accordance with claim 8, wherein the plastic contains a filler.
 10. The transport container in accordance with claim 1, wherein the walls as well as the layers of the wall sheet are manufactured continuously by means of extrusion in one production step and are made in one piece.
 11. The transport container in accordance with claim 1, wherein a plurality of walls are provided; and wherein hollow spaces located between the walls are filled with a heat-insulating material.
 12. The transport container in accordance with claim 1, wherein the inwardly disposed layer and/or the outwardly disposed layer of the wall sheet is/are adhesively bonded to the cover layer.
 13. The transport container in accordance with one of the claim 1, wherein the inwardly deposed layer and/or the outwardly disposed layer of the wall sheet is/are coextruded with the cover layer.
 14. The transport container in accordance with claim 1, wherein the wall element comprises individual segments of wall sheet elements, which are connected to one another.
 15. The transport container in accordance with claim 14, wherein the connection between the segments of the wall elements is releasable from the wall sheet elements.
 16. The transport container in accordance with claim 1, wherein a plurality of walls are provided in a wall sheet element or in a wall sheet strip; and wherein there is a vacuum in hollow spaces between the walls.
 17. The transport container in accordance with claim 16, wherein filler bodies are located in the evacuated hollow spaces.
 18. The transport container in accordance with claim 1, wherein a plurality of walls are provided in a wall sheet element or in a wall sheet strip; and wherein prefabricated vacuum panels are located in hollow spaces between the walls.
 19. The transport container in accordance with claim 1, wherein the transport container has a self-supporting design.
 20. The transport container in accordance with claim 1, wherein the transport container has a support frame design with an end frame and side members. 